Ceramic matrix composite

Abstract

A ceramic composite is produced wherein the matrix is comprised of silicon nitride and cordierite and the reinforcing phase is comprised of Si-C-containing fibers.

What is claimed is: 
     
       1. A process for producing a solid composite comprised of a ceramic matrix and at least a layer of a plurality of continuous Si-C-containing fibers which comprises forming a slurry of a matrix-forming material comprised of a particulate mixture of silicon nitride and a member selected from the group consisting of cordierite, a cordierite-forming composition, and combinations thereof wherein said member ranges from 1% to 50% by weight of said particulate mixture, providing at least a layer of a plurality of continuous fibers comprised of a Si-C containing material containing at least 50% by weight of silicon and at least 25% by weight of carbon based on the weight of said Si-C containing material, producing a wet preform comprised of said fibers coated with the wet solids of said slurry wherein the coated fibers in each layer are substantially parallel to each other and wherein the coatings prevent significant direct contact between the fibers, drying said wet preform to produce a dry preform comprised of said matrix-forming material and said fibers, and hot compressing the resulting preform or a sample thereof under a sufficient pressure at a temperature sufficient to generate sufficient liquid phase to sinter said silicon nitride and produce a sintered product, said compression temperature ranging from 1200° C. to 1750° C., and cooling said sintered product producing said solid composite, said composite having a porosity of less than 5% by volume, said composite containing no significant amount of reaction product of said fibers and said matrix, said matrix having a thermal expansion coefficient which is lower than that of said fibers, at least 10% by volume of said composite being comprised of said fibers. 
     
     
       2. The process according to claim 1, wherein said cordierite ranges from 5% to 25% by weight of said particulate mixture. 
     
     
       3. The process according to claim 1, wherein said Si-C-containing material is selected from the group consisting of silicon carbide, Si-C-O, Si-C-O-N, Si-C-O-Metal, Si-C-O-N-Metal, and mixtures thereof, wherein said O, N and metal are each present at least in an amount of 1% by weight of said Si-C-containing material. 
     
     
       4. The process according to claim 1, wherein said Si-C-containing material surrounds a core. 
     
     
       5. The process according to claim 1, wherein said fibers have a diameter greater than about 5 microns. 
     
     
       6. The process according to claim 1, wherein said matrix-forming material includes silicon carbide whiskers in an amount ranging to about 30% by weight of said matrix-forming material. 
     
     
       7. The process according to claim 1, wherein said Si-C containing material is comprised of silicon carbide. 
     
     
       8. The process according to claim 1, wherein said hot compressing is carried out by hot pressing. 
     
     
       9. The process according to claim 1, wherein said resulting preform or a sample thereof is encapsulated within a material which is pressure- and heat-transmitting at said compression temperature, wherein said hot compression is carried out by hot isostatic pressing, and wherein said encapsulating material has no significant deleterious effect on said composite. 
     
     
       10. A composite comprised of a ceramic matrix and a plurality of layers of continuous Si-C-containing fibers embedded in said matrix with no significant contact between said layers of fibers, said matrix leaving no significant portion of said Si-C-containing fibers embedded therein exposed, each said layer being comprised of a plurality of said continuous fibers, said Si-C-containing fibers comprising at least 10% by volume of said composite, said fibers being comprised of an Si-C-containing material containing at least 50% by weight of silicon and at least 25% weight of carbon based on the weight of said Si-C-containing material, each said Si-C-containing fiber having a diameter greater than 5 microns and a length at least ten times its diameter, said continuous fibers having a length greater than 1000 microns, more than 90% by volume of said fibers in each layer being spaced from each other and being at least substantially parallel to each other, said matrix being comprised of a mixture of silicon nitride, cordierite, and silicon carbide whiskers, said cordierite ranging from 1% to 50% by weight of the total amount of said silicon nitride and said cordierite, said whiskers ranging to 30% by weight of said matrix, said matrix being continuous and in direct contact with said fibers, said composite having a porosity of less than 5% by volume, said composite containing no significant amount of reaction product of said fibers and said matrix, said matrix having a thermal expansion coefficient which is lower than that of said fibers, said fibers preventing brittle fracture of said composite at a temperature ranging from 15° C. to 30° C. 
     
     
       11. The composite according to claim 10, wherein said cordierite ranges from 5% to 25% by weight of the amount of said silicon nitride and cordierite. 
     
     
       12. The composite according to claim 10, wherein said Si-C-containing material is comprised of a material selected from the group consisting of silicon carbide, Si-C-O, Si-C-O-N, Si-C-O-Metal, Si-C-O-Metal and mixtures thereof, wherein said O, N and Metal are each present at least in an amount of 1% by weight of said Si-C-containing material. 
     
     
       13. The composite according to claim 10, wherein said Si-C-containing material surrounds a core. 
     
     
       14. The composite according to claim 10, wherein said Si-C-containing material is comprised of silicon carbide. 
     
     
       15. The composite according to claim 10, which contains a plurality of layers and said fibers in a layer extend in a direction different from that of the fibers in another of said layers. 
     
     
       16. The composite according to claim 10, wherein said silicon carbide whiskers range from 10% to 25% by weight of said matrix. 
     
     
       17. The process according to claim 1, wherein said Si-C-containing material envelops a core. 
     
     
       18. The composite according to claim 10, wherein said Si-C-containing material envelops a core.